Method and apparatus for submarine signaling and detection



R. A. FESSENDEN. METHOD AND APPARATUS FOR SUBMARINE SlGNALhJG AND DETECTION.

APPLICATION FELEDI FEB. I. 19I8. Aug. 3

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R, A. FES

00 AND APPARATUS FOR SUBFIEARINE SIGNALING AND DETECTION.

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AFFLICATEON FiLED FEB. I, I9I8.

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tance apart of the ears UNITED STATES PATENT OFFICE.

REGINALD A. FESSENDEN, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR T0 SUBMA- RINE SIGNAL COMPANY, OF PORTLAND, MAINE, A CORPORATION OF MAINE.

METHOD AND APPARATUS FOR SUBMARINE SIGNALING AND DETECTION.

Specification of Letters Patent.

Patented Aug. 3, 1920.

Application filed February 1, 1918. Serial No. 214,849.

To all whom it may concern:

Be it known that I, REGINALD A. FEssnNDEN, of Brookline, in the county of Norfolk and State of Massachusetts, a citizen of the United States, have invented new and useful Improvements in Methods and Apparatus for Submarine Signaling and Detection, of which the following is the specification.

My invention relates to signaling through fluid media, such as water and air, and more especially to the elimination of disturbing impulses due to the motion of said fluid media, and more especially still to the elimination of water noises in submarine detecting and signaling.

My invention has for its object increased efficiency of signaling and detecting devices in fluid media and more especially the elimination of disturbing noises.

Figures 1 and 2 show partly diagrammatically apparatus suited for carrying out my invention.

Fig. 3 shows on line 3-3 of Fig. 4, and

Fig. 4 shows diagrammatically a vertical section of another form of apparatus for carrying out my invention.

Fig. 1 shows in plan an oil tank 14 of a destroyer 11, the parts forward and aft not being shown.

Fig. 2 shows a cross section of the destroyer through the oil tank between the points 12 and 18, 24 being the deck forming the top of the oil tank, and which is above the water line so that the tank is incompletely submerged.

15, 16, 17, and 18 are submarine signaling devices, preferably oscillators of the type described in U. S. Patent No. 1,167,366, issued January 4, 1916.

These signaling devices 15, 16, 17, 18 are preferably placedat a greater distance from each other than the product of the ratio of the wave length of sound in oil to the wave length of sound in air, into the average disof the human headfor example, twice or three times the distancein order to obtain an increased stereophonic sound effect.

19, 20, 21 are vertical sound screens acoustically insulating the oscillators 15, 16, 17, 18 from each other. This enables the direction of the signals to be obtained by listening in on one or more of the oscilladiagrammatically a section- Applicant, as a result of numerous calculations, measurements, and experiments, as certained that these water noises were divlded 1nto three distinct classes and that two of these classes of water noises were eliminated by the means and apparatus shown above or by other means and apparatus disilosed in other applications or known to The present application, while relating in part to all three classes of water noises, relates especially to the elimination of the third class of water noises. 'This class applicant discovered was produced along the water line 22, 25 of the destroyer and a large section of said noises differs very considerably in character and frequency from the other two classes of water noises which are not here discussed. These water-line noises are only troublesome when the liquid-filled tank containing the submarine apparatus is partially submerged as shown in Fig. 4; because only in this case are the noises produced at the water-line in sufficient acoustic connection with the liquid in the liquidcontaining tank. For example, if the liquidfilled tank were not partially but wholly submerged, the top 24 of the tank being lowered to about the position of the numeral 19, then the noises produced at the water-line would be acoustically insulated fromv the liquid contained in the tank by the air space extending above the top of thextank to the water line and the water-line noises would not be transmitted to. the submarine apparatus and would not disturb the receipt of the signal.

Applicant has discovered:

A. That these different types .of water noises are best handled more or less separately. r

B. That if the water line water noises are eliminated the other two types of water noises may be readily eliminated by other means not dealt With in this specification.

C. That said water line water noises have such wave lengths and other properties that water-line of the vessel, the sound screen 23, Fig. 2 (shown in dotted lines in Fig. 1) is placed in the oil tank, as shown, adjacent to the skin of the destroyer in such a way, 'as shown, that when water line water noises are made along the water line 22, by passage of the vessel through the water or by the sea, the oscillator 16 is placed in a sound shadow as regards these noises by the acoustically insulating screen, as shown.

This screen'23 preferably extends somewhat lower than the upper part of the signaling apparatus 16. in order to make a better sound shadow as regards the water line water noises.

At the same time, owing to the fact that sound waves bend slightly around the edges of an acoustic screen, the oscillator 16 is not cut off from sound traveling in a horizontal direction through the water and consequently sounds produced by a submarine are heard on the oscillator 16, although the water line water noises are not heard, 71. e. the screen 23 screens the oscillator 16 from the water line water noises but does not screen it from the submarine noises.

The acoustic screen 23' may be made in any suitable manner well known in the art or as described in applicants other'applications of may be formed of streams of air bubbles issuing from a perforated pipe, the perforated pipe occupying the position of the lower edge of the screen 23; see Figs. '3 and 4: where 27 indicates a perforated pipe and 28 the source of compressed air connected thereto, 29 being the air bubbles forming the sound screen. This pipe may be duplicated or otherwise properly located to screen the noises from any of the receivers as desired.

A second form is shown on the right hand side of Fig. 2, where the acoustic screen 26 arranged as shown (shown in him; though it is extremely difficult to eliminate all three classes of water noises simultaneously and by the same apparatus.

The problem of detecting submarines from destroyers going at speeds of twenty knots and upward and in rough weather has in this way been solved by applicant, and the method is also of use for submarine signaling generally and also in connection with aeroplane work and turbines and pro pellers.

What I claim is:

1. The method of submarine signaling and detection which consists in locating the signaling and detecting means in a partially-submerged, liquid-filled tank and below the level of the surface of the water in which the tank is partially submerged and acoustically insulating said means from the surface noises only of the submerging water whereby the sound waves originating at a distance inay reach the signaling and de-' tecting means without interference from water noises originating at or near the surface of the water.

2. A liquid-filled tank partially sub= merged in water, a signaling and detecting means located in said tank below the line 0f the surrounding water, and an acoustically-insulating means located in said tank below said water line between said signaling and detecting means and said water line whereby sound waves originating at a distance will not be interfered With by noises originating near said water line but may be received.

REGINALD A. FESSENDEN.

65 described in other applications or known to' 

